Deflection yoke core having non-cylindrical winding bearing surface



April .12, 1966 c. E. ToRscH 3,245,192

DEFLECTION YOKE CORE HAVING NoN-CYLINDRICAL WINDING BEARING SURFACE Filed June 19, 1962 3 Sheets-Sheet 1 202 59 TJ 4l',

E. i INVENTOR.

Cunmns E. Tensen @miga/510+ ggg/1f.

Hw-Toensys April i12, 1966 c. E. ToRscH 3,246,192

DEFLECTION YOKE CORE HAVING NON-CYLINDRICAL WINDING BEARING SURFACE Filed June 19, 1962 5 Sheets-Sheet 5 INVENTOR. CHnnLss E. TonscH nrroensys United States Patent O 3,246,192 DEFLECTION YOKE CORE HAVING NON-CYLIN- DRICAL WINDING BEARING SURFACE Charles E. Torsch, Lakewood, Ohio, assignor to The Muter Company, Chicago, Ill., a corporation of Illinois Filed .lune 19, 1962, Ser. No. 203,546 22 Claims. (Cl. 313-76) The present invention relates to electromagnetic deflection yoke cores for cathode ray tubes and more particularly to novel cores for deflection yokes for use in television.

Cathode ray tubes for use in television and like systems are generally provided with cathode ray beam deflection yoke assemblies for deflecting the cathode ray beam, so as to cause it to scan a fluorescent screen in a predetermined pattern. The deflection is brought about by the effect on the beam of perpendicular magnetic fields of varying intensity created by the flow of a saw tooth current through a pair of vertical and horizontal deflection coils placed about the neck of the cathode ray tube.

v Magnetic cores are generally provided adjacent or surrounding the coils for concentrating the magnetic fields inthe area of the tube where the deflection of the cathode ray beam is to take place during the scanning operation. The cores generally encircle the neck of the tube adjacent the flared or bulb portion thereof. The cores have generally been constructed round in internal cross-sectional configuration and with the internal surface terminating at the cathode ray beam entrance end in a plane surface substantially normal to the longitudinal axis of the core. Y Difllculties have existed in that the conventional yoke assemblies have utilized large amounts of copper for the coils, particularly where the cosine distribution was involved.

A further problem with the conventional yoke assemblies was thatv optimum sensitivity was not achieved, and at increasingly high anode voltages, more sweep power wasl required than was economically available within the ratings of existing driver tubes. The conventional yoke assembly had an additional disadvantage in that energy storage in the horizontal windings resulted in excess heating and a consequent loss vin efficiency of the yoke.

' Shapes other than those round in internal cross section have existed, such as the square-shaped cores which were developed for radar, and castellated, or motor-winding, types of cores. However, in addition to the objections set forth for the round core, the former type was inefficient for television purposes, and the latter provided an undesirable non-uniform field gradient.

Accordingly, it is an object of the present invention to provide a toroidal deflection yoke core suitable for use with cathode ray tubes constructed and arranged in a manner to provide a maximum flux density throughout the area in which the cathode ray beam deflection occurs, and` to accomplish this with a minimum power consumption.

A further object is to provide a core which will reduce the amount of copper required and which will do so while still utilizing a cosine distribution.

Another object is to provide a yoke assembly for use with cathode ray tube deflection systems whereby the assembly is constructed and arranged in a manner to provide. a uniform flux gradient.

A still further object is to provide a core and coil arrangement which decreases theenergy storage in the horizeontal windings and lessens the heat losses of the system.

Another object is to provide a core which protects the rear of the coil from mechanical pressure.

The foregoing objects are accomplished by providing a novel internal cross-sectional core structure, and by the construction of a pair of novel longitudinal tail fins.

3,246,192 Patented Apr. l2, 1966 Referring now to the drawings:

FIG. l shows a longitudinal elevation view of a deflection yoke assembly mounted on a cathode ray tube;

FIG. 2 is an enlarged transverse cross section of the assembly taken along line 2-2 of FIG. 1, and illustrating a preferred form of the novel cross-sectional core structure;

FIG. 3 is an enlarged front end view of the core removed from the assembly of FIG. 1;

FIG. 4 is` an axial cross section of the embodiment of FIG. 3 taken along the lines 4--4 in FIG. 3;

FIG. 5 is a front end view of the core showing a modification wherein the internal surface comprises a surface of revolution about other than one center;

FIG. 6 is a front end view of the core showing a modification wherein the internal core faces having the lesser span are substantially planar;

FIG. 7 is a front end view of the core showing a modification wherein the entire internal surface is planar;

FIG. 8 shows a longitudinal elevation view of a deflection yoke assembly utilizing a pair of novel core tail fins; the core shown is utilized'with a pair of toroidal outer windings and saddle-type inner windings;

FIG. 9 is a top View of the core shown in FIG. 8 with the core being removed from the assembly and rotated FIG. 10 is a perspective view of the modification of the core of FIG. 9;

FIG. 11 illustrates an assembly utilizing the novel core tail fins in conjunction with two pairs of saddle-type windings, with both windings rotated 90 relative to the position of the active edges of FIG. 8.

Referring again to the drawings, FIG. 1 shows a deflection yoke assembly 20 mounted on a cathode ray tube 21. The yoke assembly, which surrounds the neck of the tube, includes a pair of saddle-type horizontal deflection coils 22, an insulator 23, and a pair of toroidal-type vertical deflection coils 24, wound around a hollow ferrite core 25. A saw tooth current flowing through the deflection coils creates a pair of perpendicular magnetic fields in the neck of the tube. As is well known in the art, the relative intensities of the-se fields vary in a saw tooth fashion. A cathode ray beam 27 from an electron gun (not shown) passes through the neck of the tube on its way to the screen portion 28 of the tube and is deflected by the resultant saw tooth variations in the magnetic field in sucha manner that the beam traces a number of successive parallel lines on the screen, each slightly positioned below the preceding line so that the area scanned is generally of a rectangular shape. While the beam is scanning, the intensity of the beam varies in accordance with an input signal from the transmission station, thereby creating an image on the screen. the magnetic core, its associated deflection coils, and their effect on the scanning process.

The flow of current through the coils generates a magnetic field which is strongest in the near vicinity of the coils. In order to direct a portion, of the magnetic field into the area where the beam is to be deflected, the coils or parallel magnetically opposing. As a result of ther aforesaid arrangement, portions (not shown) of the mag-1 netic fields encircle the outside of the tube neck and escape to the atmosphere, while portions 35 and 36 turn The present invention relates to.

into the neck of the tube and cause the deflection of the cathode ray beam.

Deflection yokes are generally provided with a magnetic core which serves to concentrate the magnetic fields within the neck of the tube and to increase the efficiency of the scanning operation by reducing the reluctance of the magnetic path. As shown in FIGS. 1, 3 and 4, the core v225 is hollow, and has a front end portion 66, a rear end portion 67, an exterior peripheral surface 38 and an interior longitudinal surface 39 formed about a central axis 50. Whether the coils are of the saddle or toroidal type, a portion of each coil will be mounted substantially adjacent one face of :the interior surface of the core. The term face, as used herein, is a term of position, and each quarter 46, 47, 48 and 49, of the interior cross-sectional core surface thus constitutes a face adjacent which a corresponding coil half is mounted. The coil halves need not actually touch the face adjacent which they are mounted. For example, the coil pairs are generally separated from each other by an electrical insulator. Referring to FIG. 2, the coil halves y31'1 and 32 of the horizontal coil pair are located adjacent the core faces 46 and 47 and the coil halves 33v and 34 of the vertical coil pair 24 are located adjacent the core faces 48 and 49.

l It has been found that by constructing the interior surface of the core so that the span between the opposing internal faces adjacent which one coil pair is to be located is greater than the span between the opposing internal faces -adjacent which the other coil pair is to be located, greater sensitivity and eiiiciency is obtained, less copper is required, and the energy storage in the windings nearest the cathode ray beam is decreased. For example, referring to FIG. 2, the span between the opposing core faces 46 and 47 is greater than the span between the opposing core faces 48 and 49. The greatest span forms a major axis, and the lesser span a minor axis.

Referring to FIGS. 2 and 4, the span differential of the nolvel core structure relates to the internal surface 39 of the core. The outer surface 38, the front end 66 and the rear end 67 may be of any suitable configuration. It is preferred that the cross-sectional span-differential of the internal surface be located along the entire axial length of the core. However, improvements are achieved where the novel internal cross-sectional surface occupies only a portion thereof.

One method of constructing the internal surface is shown in the front end elevation view of FIG. 3. The view illustrates that the cross-section of the internal surface is proportionately the same as the internal surface expands axially from the rear end of the core 67 to the front end 66. The axial flaring of the core towards the front end 66 is further shown in FIG. 4. For purposes of illustration, the method of forming `the cross-sectional configuration of a plane normal to the central axis of t-he core and adjacent the rear end 67 will be described. It is to be understood that the cross-sectional configuration used .adjacent the rear end portion is enlarged proportionately as the surface progresses towards the front end in an axial taper.

Referring to the preferred embodiment of FIG. 3, the core is formed about a longitudinal central axis 50. Two opposite faces 46 and 47 each occupy substantially onefourth of the interior cross-section of the core and are spanned by a major axis M1, which is located in a plane passing through the central axis 50i. The faces-46 and 47 may be constructed by a pair of equal rad R1 and R2 located at equidistant predetermined foci, which vare spaced from the central axis 50 at equidistant points along the major axis. The two opposite faces 48 and 49 each occupy substantially one-fourth o-f the interior cross sec-tion of the core and are located substantially at right angles to the faces 46 and 47. The minor axis M2 spans the faces 48 and 49. The faces 48 and 49 are comprised in part by planar surfaces tangent to the curved surfaces defined by radii R1 and R2 and in part by the adjacent curved surfaces for the respective quarter sections. The quarter sections are schematically defined by dotted lines 61, 62, 63 and 64. It is to be understood that in the assembled position each coil half is located adjacent one particular face, but need not occupy the entire quarter-section defined by the face. Likewise, as is apparent from FIG. 2, the coil halves adjacent one face may overlap a contiguous face, but each coil is located substantially .adjacent only one face. Moreover, while a one-piece core construction is sholwn, lthe core may also be of a two-piece construction as well. In such case, t-he plane of joinder usually bisects one of the pairs of opposite faces.

Further modifications of the invention are shown in FIGS. 5, 6 and 7. In FIG. 5, the entire internal crosssectional surface is curved. In FIG. 6, the internal surface is a mixture of curved and planar surfaces wherein the planar surfaces join the curved surfaces in other than a tangential relationship. As another example, the curved surfaces might be approximated by `a series of planar surfaces, as, for example, the irregular octagonal shape shown in FIG. 7. Preferred results are achieved, however, where the surfaces spanned by the minor axis are partially planar and partially curved and wherein the surfaces spanned by the major axis are entirely curved as shown in the embodiment of FIG. 3 and the modication o-f FIG. 6.

Moreover, it is preferred that the cross-sectional internal surface be constructed about the central axis 50 so that the surface in any given plane normal -to the central axis is continually closer to the central axis as the surface progresses from the span defined by the major axis to the span defined by the minor axis as such configuration provides a more evenly gradated ilux distribution. Consequently, remote comers, such as for example, where a core rectangular in configuration is utilized, are avoided.

In order to build up a cosine coil distribution at the beam entry end of the assembly, it has been necessary in the past to construct the coils near the rear end of the core in a series of layers of progressively changing width. It has been found that the use of the cross-sectional core configuration of the present invention permits a portion of the layers nearest the interior surface of the core to be eliminated in at least one of the core pairs, while at the same time retaining substantially the same effect in overcoming defiection defocusing, as does the conventional cosine layer build-up. Moreover, the decrease in copper does not cause undesirable sudden linx gradients. The dotted line 60 in FIG. 2, illustrates where the location of the 4interior faces for one of the coil pairs would have been, had the conventional circular structure been circumscribed about the central axis 50 with the diameter of the major axis. The areas 61 and 62, located between the dotted line 60 of a corresponding circular core and the coil halves 33 and 34, indicate the amount of copper which has been saved while retaining the maximum iiux density advantage of the former structure.

It is to be understood that the present core could be utilized with a pair of saddle coils, a pair of toroidal coils, or a combination of toroid and saddle coils as shown in FIG. l.

The aforesaid structure has resulted in savings in copper, produced greater sensitivity and efficiency of the deflection yoke, and decreased the energy storage in the horizontal windings.

The purposes of the aforesaid invention may be carried out wherein the external surface of the core may be of any suitable axial or cross-sectional configuration. An improvement in the axial configuration of the core shape has been discovered, however, and may be used either in conjunction with the foregoing described novel cross-sectional configuration, or it may be used with conventional core constructions.

In the conventional coreV construction, the internal faces have been of equal axial length at the rear portion of the core, and the internal rear core surface has terminated in a plane which was substantially perpendicularto the axis ofthe core. This'arrangement is illustrated by the dotted line 58 in FIG. 9. It has been found that by constructing a pair of tail fins extending on two opposite sides of the core, a decrease in energy storage is obtained in the coil nearest the central axis of the core, and the reluctance of the magnetic circuit is noticeably diminished with a corresponding' increase in core efficiency. Moreover, the structure captures additional stray flux from the end turns thereby further adding to the yoke efficiency. In addition, adverse mechanical pressure on the windings mounted nearest the core may be removed depending on the degree of extension of the tail fins. It is preferred that the fins be integral with the interior surface 39 and slope gradually axially rearwardly from a pair of inner opposite bases, such as bases 72 and 73, shown in FIG. l0, to a pair of outer vertexes, such as are indicated at 74 and 75. The bases are preferably located adjacent one pair of core faces, and the vertexes adjacent the other pair of core faces. It is preferred that the internal surface of the fins be curved to fit the internal cross-sectional contour of the core and be integral therewith. The outer vertexes and inner bases may be in the form of points, or may be planar surfaces in a plane perpendicular to the core axis. The vertexes may have lug portions 82 and 83 located adjacent thereto to facilitate molding. The surface connecting the internal fins to the outer peripheral surface 76 of the core may be perpendicular tothe core axis, or may be beveled at an angle thereto as shown at 77. Preferably, the bases 72 and 73 are located axially at least as far rearward as is the furthest rearward extension 71 of the outer peripheral surface 76.`

i It is preferred that in the assembled position, the base portions 72 and 73 be located adjacent the winding which is furthest from the longitudial core axis and the vertexes 74 and 75 be located adjacent the winding which is near- ,est to the longtiudinal core axis. In FIG. 8, the assembly is shown Vwith a toroidal type winding 78 mounted adjacent the bases 72 and 73 with a saddle-type winding 79 adjacent the vertexes 74 and 75. The assembly is shown mounted on an insulator 23 having a rear flange 29 and a front flange 30. In FIG. l1 illustrates an assembly wherein a saddle-type coil 80 replaces the toroidal coil of FIGjS. In such arrangement the horizontal coil 79 is rotated 90 relative to the position shown in FIG. 8, so that its central flux path through the neck of the tube is displaced 90 with respect to the core. Correspondingly, the saddle-type coil Si) is placed so that its active edges and related central fiux path are rotated 90 from the positionthat the active edges and corresponding central flux path of the toroid winding of FIG. 8 had assumed.

The tail fins may be utilized with the novel cross-sectional core structure as hereinabove described, or they may be used with any conventional cross-sectional configuration. Wherethe tail fins are utilized with the novel cross-sectional core configuration it is preferred that the vertexes be located adjacent the faces spanned by the major axis.

The terms and expressions which have been used are used as terms of description and not of limitation, and there is no intention in the use of such terms and expressions of excluding any equivalents or any of the features shown, or described, or portions thereof, and it is recognized that various modifications are possible within the scope of the invention claimed.

With respect to the novel cross-sectional arrangement, the span, as defined herein, is measured in a plane normal to the longitudinal axis of the core by a transverse line passing through the central axis and connecting the center of one face to the center of its corresponding opposing face. Thus, in FIG. 3, for example, the major axis M1 comprises one transverse span, and the minor axis M2 comprises the other transverse span.

I claim:

1. A core for use in cathode ray tube deflection yokes, said core Abeing hollow and having a front end and arear end an external surface and an internal surface, said internal surface being formed about a longitudinal central axis and being defined -by at least one pair of opposing axially extending coil receiving faces which are adapted to be placed adjacent at least one defiection coil pair, and said internal surface being further defined by at least one other pair of opposing and axially extending coil receiving faces located at an angle to the said one pair of coil receiving faces, and adapted to be placed adjacent to at least one other defiection coil pair, and wherein for at least a portion of the axial length of the core the transverse span between the centers of the faces of said one pair of faces, in a plane normal to the central axis, is greater than the transverse span ybetween the centers of the faces the inner surface of said core being flared axially outwardly near the front end of the core of said other pair of faces.

2. A core according to claim 1, including at least one coil pair mounted adjacent said one pair of faces and at least one other coil pair mounted adjacent said other pair of faces.

3. A core according to claim 1, wherein said internal surface includes oppositely disposed portions projecting axially rearward so as to define a pair of oppositely dis posed fins on the internal surface at the rear end of the core.

4. A core for use in cathode ray tube deflection yokes, said core -being hollow and having an external surface and an internal surface, said internal surface being formed about a longitudinal central axis so that for at least a portion of the axial length of the core the internal surface includes at least a pair of substantially oppositely disposed and axially extending planar surfaces and a pair of substantially oppositely disposed and axially extending curved surfaces.

5. A core according to claim 4, wherein the planar surfaces are located intermittent the curved surfaces and wherein, in a plane normal to the longitudinal central axis, the transverseV span between the centers of the curved surfaces are greater than the transverse span between the centers of the planar surfaces.

6. A core according to claim 5, wherein the curved surfaces are circular segments constructed about axes other than the longitudinal central axis.

7. A core according to claim 6, wherein the planar surfaces are tangential to the curved surfaces.

8. A core assembly according to claim 5, including a toroid type opposing coil pair, mounted adjacent the said planar surfaces.

9. A core according to claim 8, wherein the said toroid coil pair is of an effective cosine distribution.

10. A core for use in cathode ray tube deflection yokes, said core having an outer surface and an inner surface formed about a longitudinal central axis, said inner surface having at least one pair opposed coil receiving of faces and at least one other pair of opposed coil receiving faces located at an angle to said one pair of faces, said core having a front end adapted to be placed adjacent the beam exit end of a cathode ray beam deflection yoke and a rear end adapted to -be placed adjacent the beam en,- trance end of a cathode ray beam defiection yoke, with the length of the inner surface defined by said one pair of opposed coil receiving faces extending further rearward axially at the rear end of the core than is the furthest rearward axial extension of the inner surface defined by the other pair of faces.

11. A core according to claim 10, wherein the cross sectional span of the inner surface defined by the said one pair of opposed faces adjacent the commencement of the said further rearward extension is substantially -the same 7 as the cross sectional configuration of the interior core surface adjacent the fins at the rear end of the core.

12. A core according to claim 10, wherein. the furthest rearward extensions of the said other pair of faces of the rear internal core surface are located at least as fa-r rearward axially as is the rearward ax-ial projection of the majority of the outer peripheral surface of the core.

13. A yoke assembly including a core according to claim 10, a cathode ray tube, a cathode ray gun at one end of the tube and a screen at the other end thereof, said core being mounted on the cathode ray tube so that the said rear end of the core is oriented in the direction of the said gun and the front end of the core is oriented inthe direction of the said screen.

14. A core according to claim 10 wherein the rear end of the core includes a connecting surface for connecting the said inner surface and outer surface, the majority of said connecting surface being substantially frusto-conical in shape with .the apex of the cone being oriented in the general direction toward the rear end of the core.

15. A core for use in cathode ray deflection yokes, said core being hollow and having an external surface and an internal surface, said internal surface being formed about a longitudinal central axis and being defined by at least one pair of opposing axially extending coil receiving faces and at least one other pair of opposing and axially extending coil receiving faces located at an angle relative to the said one pair of coil receiving faces, and wherein for at least a portion of the axial length of the core the transverse span between the centers of the faces of-said one pair of faces, in a plane normal to the central axis, is greater than the transverse span between the centers of the faces of said other pair of faces, and wherein at least one of the pairs of opposing coil receiving faces is comprised of more than` one plane surface.

16. A core` according to claim 22, wherein for the said portion of the axial length of the core, the internal surface of the core is substantially planar and is defined by at least ysix axially extending planes.

17. A cathode raytube deflection yoke, said yoke including a hollow core, said core having an external surface and an internal surface, said internal surface being formed about a longitudinal central axis and being defined by at least one pair of opposing axially extending coil receiving faces and said internal surface being further defined by at least one other pair of opposing and axially extending coil receiving faces located at an angle relative to the said one pair of coil receiving faces, at least one deflection coil pair ldisposed adjacent said one pair of coil receiving faces, at least .one other deflection coil pair disposed adjacent said other pair of coil receiving faces, and wherein for at least a portion of the axial length of the core, theptransverse span between the centers of the faces of said one pair of faces, and a plane normal to the central axis, is greater than the transverse span between the centers of the faces of said other pair of faces, the said coils being disposed for connection to a source of power so that upon energization thereof by the power source, a first magnetic field is produced spall-A ning the said one pair yof faces and a second magnetic field lis produced spanning the said other pair of faces at an angle to the first magnetic field for deilecting a cathode ray beam passing axially through the deflection yoke.

18. A core according to claim 17, wherein the said one pair of faces are substantially at right angles to the said other pair of faces, so that the said spans define major and minor axes in a plane perpendicular to the central axis of the core, and wherein said internal core surface becomes progressively closer to the central axis as the surface progresses in said plane from said major axis to said minor axis.

19. A core according to claim 17, wherein all of the faces are curved.

20. A core according to claim 17, wherein the faces of at least portions of said other pair of opposing faces are planar and wherein said one pair of opposing faces are curved surfaces.

21. A core according to claim 20, wherein the remaining portions of the faces of the said other pair of opposing faces comprise continuations of the curved surfaces of said one pair of opposing faces.

22. A core for use in cathode ray tube deflection yoke's,

- the core comprising, in combination, an' external surface and an internal surface, said internal surface being formed about a longitudinal central axis and being defined by at least a pair of axially extending planar coil receiving faces, and at least one other pair of axially extending curved coil receiving faces, said planar surfaces being located intermittent the curved surfaces and wherein, in a plane normal to the longitudinal central axis, the transverse span between the centers of the curved surfaces is greater than the span between the centers of the planar surfaces, said core having a front end adapted to be placed adjacent the beam exit end of a deflection coil yoke, and a rear end adapted to be placed adjacent the beam er1- trance end of a deflection yoke coil, the length of the inner surface defined by said one pair of coil receiving faces extending axially further rearward at the rear end of the core then is the furthest axial extension of the inner sur# face defined by the other pair of coil receiving faces.

References Cited by the Examiner UNITED STATES PATENTS 2,586,657 2/1952 Holt 336-221 2,692,978 10/1954 Galt 336-233 2,980,815 4/1961 Ecker 313-76 3,045,139 7/1962 Lutz 317-200 3,068,436 12/1962 Holmberg et al 336-212 3,075,131 v1/ 1963 Snyder 317-200 3,081,420 3/1963 Marley 317-200 3,165,677 1/1965 Gostyn et al 3117-200 FOREIGN PATENTS 1,100,710 4/1955 France.

GEORGE N. WESTBY, Primary Examiner.

JOHN P. WILDMAN, ROBERT SEGAL, Examiners. 

4. A CORE FOR USE IN CATHODE RAY TUBE DEFLECTION YOKES, SAID CORE BEING HOLLOW AND HAVING AN EXTERNAL SURFACE AND AN INTERNAL SURFACE, SAID INTERNAL SURFACE BEING FORMED ABOUT A LONGITUDINAL CENTRAL AXIS SO THAT FOR AT LEAST A PORTION OF THE AXIAL LENGTH OF THE CORE THE INTERNAL SURFACE INCLUDES AT LEAST A PAIR OF SUBSTANTIALLY OPPOSITELY DISPOSED AND AXIALLY EXTENDING PLANAR SURFACES AND A PAIR OF SUBSTANTIALLY OPPOSITELY DISPOSED AND AXIALLY EXTENDING CURVED SURFACES. 